It has been found that adenosine 5′-diphosphate (ADP) acts as a key mediator of thrombosis. ADP-induced platelet aggregation is mediated by the P2Y12 receptor subtype is located on the platelet membrane. The P2Y12 receptor (also known as P2T, P2YADP or P2TAC) is a G-protein coupled receptor primarily involved in mediating platelet activation/aggregation.
WO99/05143 discloses generically a series of triazolo[4,5-d]pyrimidine compounds having activity as P2T (also known as P2Y12, P2YADP or P2TAC) antagonists. Recently, a new class of direct (non-prodrug) P2T receptor antagonists has been described which offers significant improvements over other anti-thrombotic agents. International Patent Application WO00/34283 discloses novel “direct” P2T receptor antagonists, including the compound of formula (I). WO01/92262 discloses crystalline and amorphous forms of the compound of formula (I).
WO01/92263 discloses a process for preparing [1S-[1α,2α,3β(1S*,2R*),5β]]-3-[7-[2-(3,4-difluorophenyl)-cyclopropylamino]-5-(propylthio)-3H-1,2,3-triazolo[4,5-d]pyrimidin-3-yl]-5-(2-hydroxyethoxy)cyclopentane-1,2-diol (alternatively named (1S,2S,3R,5S)-3-[7-{[(1R,2S)-2-(3,4-Difluorophenyl)cyclopropyl]amino}-5-(propylsulfanyl)-3H-[1,2,3]triazolo[4,5-d]pyrimidin-3-yl]-5-(2-hydroxyethoxy)-1,2-cyclopentanediol).
The present invention provides an improved process for preparing a compound of formula (I). In particular, the process according to the present invention provides improved yield of the compound of formula (I) compared to previous processes as well as improved process efficiency and higher purity of the compound of formula (III). A high quality of the compound of formula (I) is obtained without recrystallisation.